用XMM-牛顿数据研究四个星系团的X射线子结构
X-ray Substructure Studies of Four Galaxy Clusters using XMM-Newton Data
摘要：
Mahdavi等人发现弱透镜效应和X射线质量测量之间的一致程度是星系团半径的函数。数值模拟还指出，X射线质量代理在所有半径下的工作效果并不相同。该效应的起源被认为与集群合并有关。最近的工作提出的集群地图显示的能力，X射线地图揭示和研究集群合并的细节。在这里，我们提出了第一次尝试使用的子结构的研究，在评估系统的流体静力学质量测量使用二维（2-D）X射线诊断。温度图是唯一能够识别的子结构在一个几乎松弛的集群，这将是在ICM电子数密度和压力图中被忽视。我们描述的径向波动的2-D地图的累积/微分散射配置文件相对于平均配置文件内/在一个给定的半径。幅度表明温度、电子数密度和熵图中有~10次波动，压力图中有~15次波动。散射的幅度和不连续性补充2-D子结构诊断，例如，指示最受干扰的径向范围。有一个诱人的链接之间的子结构确定使用的熵和压力波动的分散和流体静力学质量偏差相对于预期的质量的基础上的M-Yx和M-Mgas关系，特别是在r500。XMM-牛顿观测来自集群的~ 120，000个源光子足以通过光谱测量的2-D温度，电子数密度，熵和压力图应用我们的子结构诊断。
英文摘要：
Mahdavi et al. find that the degree of agreement between weak lensing and X-ray mass measurements is a function of cluster radius. Numerical simulations also point out that X-ray mass proxies do not work equally well at all radii. The origin of the effect is thought to be associated with cluster mergers. Recent work presenting the cluster maps showed an ability of X-ray maps to reveal and study cluster mergers in detail. Here we present a first attempt to use the study of substructure in assessing the systematics of the hydrostatic mass measurements using two-dimensional (2-D) X-ray diagnostics. The temperature map is uniquely able to identify the substructure in an almost relaxed cluster which would be unnoticed in the ICM electron number density and pressure maps. We describe the radial fluctuations in the 2-D maps by a cumulative/differential scatter profile relative to the mean profile within/at a given radius. The amplitude indicates ~10 fluctuations in the temperature, electron number density and entropy maps, and ~15 fluctuations in the pressure map. The amplitude of and the discontinuity in the scatter complement 2-D substructure diagnostics, e.g. indicating the most disturbed radial range. There is a tantalizing link between the substructure identified using the scatter of the entropy and pressure fluctuations and the hydrostatic mass bias relative to the expected mass based on the M-Yx and M-Mgas relations particularly at r500. XMM-Newton observations with ~120,000 source photons from the cluster are sufficient to apply our substructure diagnostics via the spectrally measured 2-D temperature, electron number density, entropy and pressure maps.
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